1. Background Field
This disclosure relates generally to systems, apparatus and methods for estimating a position for a base station, and more particularly to estimating the coverage area of the level 3 region to which a base station belongs.
2. Relevant Background
Obtaining accurate position information for mobile devices, such as cellular telephones or other wireless communication devices, is becoming prevalent in the communications industry. A common means to determine the location of a device is to use a satellite positioning system (SPS), such as the well-known Global Positioning Satellite (GPS) system or Global Navigation Satellite System (GNSS), which employ a number of satellites that are in orbit around the Earth.
An SPS positioning system requires that the mobile device lock on to signals from a number of satellites, e.g., at least four, that are visible from the current position of the mobile device. If a mobile device is moved a significant distance while the SPS positioning system is turned off, e.g., when a user travels by airline to another city, the mobile device will need to acquire a new set of satellite signals to perform a position fix. The mobile device, accordingly, must perform a cold start as the last position fix of the mobile device is unknown. A cold start may take a considerable time, as long as twelve minutes, because the receiver must search through all of the codes and frequency combinations to locate a satellite at the new position. With an approximate position fix for the mobile device, however, the number of satellites that are possibly visible to the mobile device can be reduced and consequently, the time required to search for satellite signals may be reduced.
A terrestrial based position fix, e.g., using known locations of base stations with which the mobile device is in wireless communication, is a commonly used technique for obtaining an approximate position fix. Base station locations may be stored in a base station almanac (BS almanac) database and may be communicated to the mobile device via the base station. Typically, BS almanac databases are built up over time based on, e.g., crowdsourced information for the base stations. While a BS almanac database is being built, or when new base stations are added to a wireless network, the BS almanac database may be incomplete. Consequently, mobile devices in contact with a base station that is not yet included in the BS almanac database may not be able to acquire an approximate position fix from that base station, which may markedly increase the time required to achieve a satellite lock.